EP0444997B1 - Circuit for controlling the power supply of a plurality of electronic modules - Google Patents

Description

The present invention relates to a device for controlling the electrical supply of a plurality of electronic modules and, more particularly, to such a device making it possible to selectively control this supply depending on whether the device is in standby state or when active state.

Today's motor vehicles are increasingly loaded with electronic modules associated with sensors and actuators to provide control functions for organs such as headlights, wipers, displays of on-board computers, etc. fuel injection control in an internal combustion engine propelling the vehicle, adaptive suspension control or anti-lock of the vehicle wheels. It is now envisaged to electrically supply these modules with a common supply line or bus and to interconnect the modules with a local multiplexed communications system comprising a data bus common to all the modules.

When the vehicle is operating, such a multiplexed system consumes a lot of energy and can draw on the battery from 2 to 25 amps for example, depending on the electrical performance requested.

When the vehicle is stationary, the power consumption should be limited to a low value (less than 3 milliamps for example) to save the energy stored in the battery. Publication EP-A-0 327 456 proposes the operational state and a standby state of the electronic boxes by means of messages circulating in a communication channel to which these boxes are connected. For this, it is necessary to stop supplying the modules via the supply bus by isolating the latter from the battery. When the system is thus put in the "standby" state, it is however necessary that the request for certain functions is capable of "waking up" the entire system. This is the case, for example, when the driver actuates an ignition key to start the vehicle. It is then necessary that certain parts of the modules remain supplied in standby state, to allow the system to "wake up".

According to a known procedure, the current consumed in the standby state, an excess by this current of a predetermined level being considered as significant of an activity such that this excess then triggers the awakening of the entire system.

Such a procedure has various drawbacks. Indeed, the threshold is then a function of the number of modules or stations which are likely to wake up the system. This threshold must then be adjusted according to the "options" present in the vehicle, options which are known to be chosen arbitrarily by the vehicle owner from a list of options made available by the manufacturer.

In addition, the detection of a current threshold being exceeded does not make it possible to identify the module which is at the origin of the system awakening. Such an identification would however be advantageous in that it would make it possible to seek in priority the function which is at the origin of the alarm clock.

It should also be noted that the detection of the crossing of a current threshold, of an analogous nature, implies the use of threshold circuits made of passive components. We know that these have electrical characteristics affected by large dispersions and drifts over time. Such components are also sensitive to strong electromagnetic disturbances that are observed in the environment of a motor vehicle.

The present invention therefore aims to provide a device for controlling the electrical supply of a plurality of electronic modules, which does not have these drawbacks of the devices of the prior art.

In particular, the object of the present invention is to produce such a device equipped with means for awakening the entire device which do not require adjustments as a function of the consumption of the modules capable of waking up the device.

The present invention also aims to produce such a device which is well immune to noise due to electrical and electromagnetic disturbances present in the environment of a motor vehicle.

Another object of the present invention is to produce such a device which comprises means for identifying the module which is responsible for waking the device.

These objects of the invention are achieved, as well as others which will appear in the following of this description, with a device for controlling the electrical supply of a plurality of electronic modules interconnected by a data bus with a unit. data processing center, of the type which includes a common power supply line for the modules, this device being remarkable in that it comprises means installed in the central unit and sensitive to a predetermined state of the device for controlling its setting in the standby state by cutting off the supply of the modules via the common line and then ensuring the electrical supply of at least one circuit for generating wake-up signals forming part of a module, by means of at least a line of the data bus, and means sensitive to the wake-up signals emitted by the circuit for generating such signals, to cut off the supply of the modules by the donation bus and to restore the power supply to the modules via the common power supply line.

By thus cutting, during standby, the general supply of the modules by this line, the consumption of the device is greatly reduced. However, in order to then supply the parts of the modules which must remain energized for controlling the awakening of the device, the data bus is unexpectedly used for this purpose, this being normally intended for any other use.

According to the invention, at least one of the modules comprises means for selectively triggering a circuit for generating associated wake-up signals, a coupling circuit associated with this generation circuit for transmitting these signals over the data bus and a detection circuit. interposed between the bus and the central unit and sensitive to these signals to transmit to the central unit control information for waking up the device.

The device further comprises a voltage regulator put into service by the central unit when the supply of the modules is cut off by the common supply line, to supply the detection circuit and, through the data bus, the circuit coupling and the wake-up signal generation circuit of each module equipped with such circuits.

The wake-up signal generation circuit generates a pulse sequence, the coupling circuit comprising means for modulating, under the control of this sequence, the current flowing in the line of the data bus used for supplying a part of the module in standby period, the detection circuit being sensitive to this modulated current for transmitting wake-up information to the central unit.

According to an advantageous embodiment of the device according to the invention, the modulation means is a transistor whose emitter-collector circuit is connected between ground and the line of the data bus which serves as a supply line in standby period, the circuit for generating wake-up signals controlling the base of this transistor to modulate the current in this line.

According to an advantageous characteristic of the device according to the invention, the pulse sequence emitted by a module is specific to it and the central unit comprises means for identifying the module emitting the sequence, from the signal transmitted by the detection circuit.

• la figure 1 est un diagramme fonctionnel du dispositif de commande d'alimentation électrique suivant l'invention, et
• la figure 2 est un schéma électrique d'un circuit de couplage interposé entre un circuit de génération de signaux de réveil et le bus de données qui interconnecte les différents modules électroniques formant partie du dispositif suivant l'invention.

Other characteristics and advantages of the device according to the invention will appear on reading the description which follows and on examining the appended drawing in which:

• FIG. 1 is a functional diagram of the electrical supply control device according to the invention, and
• FIG. 2 is an electrical diagram of a coupling circuit interposed between a circuit for generating wake-up signals and the data bus which interconnects the various electronic modules forming part of the device according to the invention.

Referring to Figure 1 of the accompanying drawing where it appears that the control device according to the invention comprises several electronic modules M1, M2, etc ... powered by a source of continuous electrical energy 1 via two common lines 2, 3 respectively connected to the positive and negative terminals of the source 1. In the case where the device is on board a motor vehicle, the source of electrical energy is constituted by the vehicle battery. Lines 2, 3 thus constitute a "supply bus" to which voltage regulators 4, 4 ′, etc. are connected, each forming part of one of the modules M1, M2, respectively, to supply it with power. after awakening of said module, as will be seen in the remainder of this description.

The modules each provide a specific application. For example, an electronic module can be associated with a block of joysticks placed in a motor vehicle near the steering wheel, to allow the driver to control the issuance of activation / deactivation orders of various components of the vehicle. Another module can also be associated with an optical unit of the vehicle to process orders of switching on / off of headlights, position lights, etc. All the modules are interconnected with each other and with a central data processing unit 5, as is the case in particular in a "bodywork" or "class A" multiplex network where this unit centralizes the intelligence necessary for the execution of the various functions for controlling headlights, lights, windshield wipers, displaying data on an on-board computer, etc.

For the execution of the functions assigned to it, a module M1, M2 includes a protocol controller 6,6 ′ interposed between a data bus 7 common to all the modules and to the central unit 5, and means 8, 8 ′ respectively, each constituting an application circuit specific to the functions performed (switching on or off a bulb, counting pulses to determine the distance traveled and the speed of the vehicle, etc.).

According to a preferred embodiment of the invention, the data bus is a two-line bus (DATA, DATA ) powered by differential digital signals, in particular for reasons of noise immunity.

The protocol controller 6,6 ′ of each module M1, M2, regulates the exchange of information between the data bus and the associated application circuit 8, 8 ′. This can, for example, be performed in very high integration wired logic (VLSI, according to Anglo-Saxon terminology).

Some modules can be equipped with means designed to trigger the awakening of the entire device, while other modules are not equipped with such means. By way of example, a module associated with the lever block of a motor vehicle must be equipped with such wake-up means because it is in this block that the driver introduces an ignition key to control the starting of the engine. The rotation of this key must cause the device to wake up from a standby state previously established to minimize the power consumption of the vehicle, for example during a standstill thereof. Other modules must also be able to wake up the device, for example a module associated with a vehicle defense system against intrusions. The invention is particularly interested in the organization of modules such as modules M1 or M2.

In these modules, the protocol controller is interconnected to the data bus 7 through a line transceiver 9, 9 ′, possibly associated with filter 10, 10 ′, an isolation circuit 11, 11 ′ from the transmitter -Receiver being further provided for a purpose which will be explained later. The latter circuit is itself supplied by the voltage regulator 4, 4 ′, just like the protocol controller 6, 6 ′.

The modules M1 and M2 further each comprise a circuit for generating wake-up signals 12, 12 ′, respectively, activated by a trigger means such as a switch 13, 13 ′. Such a switch can be closed by the introduction of an ignition key into the lock of a lever block of a motor vehicle, as seen above. The introduction of such a key being significant of a starting action of the vehicle, it is then necessary to "wake up" the electronic modules which control various actuators incorporated in this vehicle. According to the invention, this awakening is caused by the emission of a sequence of signals generated by the generation circuit 12 and transmitted to the central unit 5 via a coupling circuit 14 (or 14 ′ in module M2), a detection circuit 15 and a possible filtering circuit 16.

According to an essential characteristic of the device according to the invention, the electrical consumption of all the modules is reduced during the standby period, by cutting off the supply of these modules by the supply bus 2, 3 and then only supplying the circuits required to wake up the assembly, via the data bus. We can choose at this effect only one of the lines of this bus, for example the line DATA , as shown in Figure 1 where it appears that this line supplies the coupling circuits 14, 14 ′ via connection lines 21, 21 ′, respectively. This power supply then replaces that established during a period of complete activity of the modules, by connection lines 22, 22 ′ to line 2 of the power bus.

The power supply in standby time of the only circuits necessary for the transmission and processing of the wake-up signals, makes it possible to considerably reduce the electrical consumption of the modules compared to that which is observed when all the electronic modules are active, (commonly, 2 to 25 amps). We can then reduce in standby period, to less than 3 mA for example, the current consumption of the device, drawn from the vehicle battery, consumption which is considered as bearable by it for long periods, corresponding to those during which the vehicle is not in service.

When the vehicle goes from a period of activity to a period of inactivity, it is therefore necessary to switch the supply of the modules from the supply bus to the data bus. This passage can be easily detected, for example, by removing the ignition key from the lever block. The central unit 5 thus prevented, opens a disconnector 17 which cuts the connection of the line 2 to the battery 1 and closes a switch 18 to ensure the connection to the battery of a voltage regulator 19 which supplies the line DATA of the data bus, the detection circuit 15 and the filtering circuit 16. The circuits 12, 12 ′ and 14, 14 ′ of the modules M1 and M2 respectively are then supplied by the line DATA while the voltage regulators 4, 4 ′ cease to be supplied by the battery, the line 2 being cut. It follows that the protocol controllers 6, 6 ′ and the application circuits 8, 8 ′ normally supplied by the regulators 4, 4 ′ stop being supplied, which greatly reduces the current required from the battery.

According to an advantageous implementation of the present invention, the isolation circuits 11, 11 ′ are normally supplied by the regulators 4, 4 ′ respectively, to ensure the transmission of information coming from the data bus 7 to the protocol controllers 6, 6 ′ respectively. When the device according to the invention is put into standby mode, the power supply to these circuits is cut off, to prevent the current coming, in standby state, from the DATA line from coming to supply the protocol controllers 6, 6 ′ through line transceivers 9, 9 ′.

The power supply of the device being thus adjusted for a standby state, only the circuits 12, 12 ′, 14, 14 ′, 15 and 16 remain active. When the switch 13 is closed, for example, signifying that all the modules must be reactivated, the circuit 12 supplied with electrical energy by an ALIM line via the coupling circuit 14, supplies the latter a sequence of "wake-up" signals. The coupling circuit 14, which will be described later in detail in connection with FIG. 2, then modulates the supply current which it receives from the line DATA by the control line 15, according to the sequence of signals received from the circuit 12, so as to establish on the line DATA current signals suitable for being read by the detection circuit 15 and filtered by the circuit 16, before being transmitted to the central unit 5 by a line 20. The purpose of the filtering is to eliminate parasitic pulses of duration not calibrated, induced by possible electromagnetic interference from the data bus.

According to an advantageous characteristic of the device according to the invention, the sequence of signals emitted by the circuit 12 is particular to the module from which it originates and the central unit can then identify this module by recognizing the particular sequence attached to it. This identification gives the central unit the possibility of modulating the awakening of the device as a function of the origin of the awakening action, as we saw above in the preamble to this description.

A software for "awakening detection" installed in the central unit 5 decodes the sequence of signals received from line 20 and in return commands the closing of the disconnector 17 and the opening of the switch 18, to restore the power supply to the modules via the power bus, as appropriate in normal operation of these modules.

To control, in the opposite direction, the passage of the power supply of the device in "standby" mode, the central unit includes other software designed to analyze the multiplexed signals received by the data bus 7, to deduce a possible transition to the inactive state of the vehicle and then switch the power supply to this device in the "standby" configuration. To do this, this software can be sensitive for example, to the absence, for a predetermined time, of signals normally received from certain sensors or actuators, significant absence of inactivity of the vehicle. As we saw above, the withdrawal of the ignition key is a significant action of a transition to the inactive state of the vehicle which can be detected and interpreted in this sense by the software for "detection of transition to mode standby".

Having thus described the operation of the control device according to the invention, both in its passage into standby state and in its awakening from such a state, as a result of a wake-up action detected by the switch 13 of the module M1 , it is not necessary to repeat this description for the module M2 which is composed of circuits identical to those of the module M1 and which functions in the same way.

Before going on to the description of the structure and operation of the coupling circuit 14 introduced between the circuit 12 and the data bus 7, it is useful to return to the nature of the signals carried by this data bus.

According to an advantageous implementation of the present invention, it is preferable to work on this bus "in current" rather than in voltage because, in the medium highly disturbed from the electromagnetic point of view that constitutes a motor vehicle, it thus overcomes number of parasitic voltage signals induced electromagnetically in the bus by the environment. The information circulating on the data bus in the form of current pulses, the role of the line transceivers is to ensure a current / voltage conversion of these pulses to make them intelligible to the protocol controllers and a voltage / current conversion from a controller to the bus.

It will also be noted that the fact of working with current on the data bus eventually makes it possible to dispense with the switch 18. The data bus is then permanently supplied by the voltage regulator, in standby state or in normal operation, which does not affect the detection of current pulses flowing in this bus.

Reference is made to FIG. 2 of the appended drawing in which a diagram of a coupling circuit such as circuit 14 of the module M1 has been shown. This circuit is connected by a line 22 to line 2 of the power bus connected to the positive pole of the battery 1. The circuit is also connected to the line DATA from the data bus 7 via line 21 and supplies the generation circuit 12 with wake-up signals via the line ALIM, this circuit 12 delivering corresponding pulses IMP to the coupling circuit, to modulate the current in the line DATA as will be explained later.

The generation circuit 12 requires a reset synchronous RESET with the passage of the device in standby state. At this passage, line 22 goes to a low voltage level and this level is transmitted to the reset input of the circuit 12 by a line 23, through a filtering circuit (C1, R2) capable of absorbing the voltage pulse which appears when the vehicle engine is started. Load resistors R1 and R7 are introduced between line 22 and line 23 on the one hand, between the filter inlet (C1, R2) and ground on the other hand.

Line 22 is connected to the supply line ALIM of circuit 12 via a diode D1. A Zener diode Z1, of 10 volts breakdown voltage for example, protects circuit 12 from overvoltages on line 22. Realized in current CMOS technology, circuit 12 can withstand voltages up to 18 volts. It is therefore well protected by the Zener diode Z1.

A capacitor C2 is placed in parallel on the diode Z1, between the input ALIM of the circuit 12 and the ground. Capacity C2 filters out transient disturbances in the supply.

In standby mode, the power to circuit 12 is provided by the line DATA connected to the ALIM input of the circuit via a diode D2 and a resistor R6 forming part of a filtering circuit (C2, R6). This supply voltage is +5 volts for example. The diode Z1 is then blocked and does not consume. Diode D1 is also blocked and prevents the passage of current from the line DATA to line 22.

When the system is not in standby mode, the diode D1 prevents the supply voltage of circuit 12 from following the voltage of the battery when it drops suddenly (when starting the vehicle for example) and then ensures the diode D2 blocked.

The actual coupling section of circuit 14 is constituted by a transistor T1, of the NPN type for example, whose collector-emitter circuit is connected between the line DATA and mass. A load resistor R3 is placed on the collector of transistor T1. The base of transistor T1 is connected to the midpoint of a voltage divider made up of resistors (R4, R5), a capacitance C3 transmitting to this bridge the voltage pulses IMP constituting a sequence of wake-up pulses emitted by the circuit 12 following the closing of the switch 13 (see FIG. 1). The capacity C3 has the function of blocking the consumption of the circuit 12 if the output of the latter blocks in logic state 1.

Thus the conduction of transistor T1 is modulated by the wake-up pulses IMP. The transistor T1 then modulates the current in the line in accordance with these pulses. DATA . The current pulses thus introduced on this line are read by the detection circuit 15 and filtered by the circuit 16 which delivers to the central unit 5 logic signals which are decoded by the latter and converted into a command to wake up the device. according to the invention, by closing the disconnector 17.

By way of nonlimiting example, the values of the resistors R3, R4 and R5 can be chosen so that the transistor T1 establishes a current pulse of 27 mA amplitude in the line. DATA when the signal delivered by the output IMP of circuit 12 is at logic level 1. The capacity C3 can be chosen so as to limit the current consumption to a time interval of 10 ms, in the event of blocking of the input IMP at the high state.

In the embodiment considered above where the line DATA is constantly supplied by the regulator 19 (no switch 18), the fact of working with current on the data bus makes it possible not to drop the nominal voltage of the bus when the device is not in standby mode. In this way, the parasitic capacities which may exist between the data bus and the chassis of the vehicle are overcome.

• limiter la consommation de courant du dispositif en état de veille,
• disposer d'un matériel réalisé avec des circuits numériques dont le fonctionnement ne dépend pas de dérives en température de composants électroniques,
• disposer d'un matériel qui n'exige pas de réglage en fonction du nombre de modules interconnectés dans le dispositif,
• protéger le dispositif des effets de perturbations électriques ou électromagnétiques induites et/ou de variations de la tension de la batterie,
• permettre l'identification du module qui est à l'origine d'un réveil du dispositif.

It now appears that the announced aims of the device according to the invention are achieved, namely:

• limit the current consumption of the device in standby state,
• have equipment made with circuits digital whose operation does not depend on temperature drifts of electronic components,
• have equipment that does not require adjustment based on the number of modules interconnected in the device,
• protect the device from the effects of induced electrical or electromagnetic disturbances and / or variations in the battery voltage,
• allow the identification of the module which is the cause of a wake-up of the device.

Of course, the invention is not limited to the embodiment described and shown which has been given only by way of example.

Claims (12)

1. A control device for the electrical supply of a plurality of electronic modules (M1, M2) interconnected by a data bus (7) with a central data processing unit (5), of the type comprising a common electrical supply line (2) for the modules, characterised in that it comprises means installed in the central unit (5) and sensitive to a predetermined state of the device in order to control its transition into a waiting state by cutting off the supply to the modules (M1, M2) from the common line (2) and then providing for the electrical supply of at least one re-actuation signal generation circuit (12, 12′) forming part of a module by means of at least one data bus line (DATA), and means (15, 16, 5) sensitive to the re-actuation signals transmitted by the circuit (12, 12′) generating these signals, in order to cut off the supply to the modules from the data bus (7) and to re-establish the supply to the modules from the common electrical supply line (2).
2. A device as claimed in claim 1, characterised in that the central unit (5) comprises software means for detecting a waiting state by processing information transmitted from the modules and transmitted to the central unit (5) by the data bus (7).
3. A device as claimed in claim 2, characterised in that at least one of the modules comprises means (13, 13′) for selectively triggering an associated re-actuation signal generation circuit (12, 12′), a coupling circuit (14, 14′) associated with this generation circuit for transmitting these signals to the data bus (7) and a detection circuit (15) interposed between the bus (7) and the central unit (5) and sensitive to these signals in order to transmit an instruction to re-actuate the device to the central unit (5).
4. A device as claimed in claim 3, characterised in that it comprises a voltage regulator (19) brought into operation by the central unit (5) when the supply to the modules from the common supply line (2) is cut off, in order to supply the detection circuit (12, 12′) and, via the data bus (7), the coupling circuit (14, 14′) and the re-actuation signal generation circuit (12, 12′) of each module equipped with these circuits.
5. A device as claimed in any one of claims 3 and 4, characterised in that each of these modules (M1, M2) further comprises a circuit (11, 11′), controlled by the transition to the waiting state of the device, in order to isolate the remainder of the module from the supply then provided by the data bus (7).
6. A device as claimed in claim 5, characterised in that each of the modules (M1, M2) comprises a protocol controller (6, 6′) interconnected with the data bus (7) by means of a line transmitter-receiver (9, 9′), the isolation circuit (11, 11′) controlling the actuation or disactivation of this transmitter-receiver (9, 9′).
7. A device as claimed in claim 3, characterised in that the re-actuation signal generation circuit (12, 12′) generates a pulse sequence, in that the coupling circuit (14, 14′) comprises a means (T1) for modulating, under the control of this sequence, the current circulating in the line (DATA) of the data bus used for the supply of a part of the module in the waiting state, the detection circuit (12, 12′) being sensitive to this modulated current in order to transmit a re-actuation instruction to the central unit.
8. A device as claimed in claim 7, characterised in that the modulation means is a transistor (T1) whose emitter-collector circuit is connected between earth and the line of the data bus (7) acting as a supply line in the waiting state and in that the re-actuation signal generation circuit (12, 12′) controls the base of this transistor (T1) in order to modulate the current in this line.
9. A device as claimed in claim 8, characterised in that the pulse sequence transmitted by a module is specific thereto and in that the central unit (5) comprises means for identifying the module transmitting the sequence from the signals (IMP) received from the detection circuit (12, 12′).
10. A device as claimed in any one of claims 3 to 9, characterised in that the coupling circuit (14, 14′) is sensitive to the discontinuation of the supply from the common line (2) in order to control the initialisation of the re-actuation signal generation circuit (12, 12′).
11. A device as claimed in any one of claims 3 to 10, characterised in that the means for selectively triggering a re-actuation signal generation circuit (12, 12′) is formed by a switch (13, 13′) whose switching controls the excitation of this circuit and in that the switching of this switch is triggered by an action indicative of a re-actuation of the device.
12. A device as claimed in claim 11, adapted to be installed in an automobile vehicle, characterised in that the switch (13, 13′) is switched by the insertion of a contact key into a lock, prior to the starting of the vehicle.

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